The proposed investigation is directed toward the solution of a very real problem in myelin research: how a virtually inaccessible self-antigen, the myelin basic protein molecule (MBP), can serve as the necessarily accessible focal point and/or receptor in the CNS for MPB-specific T-cells that effect the induction of expeimental allergic encephalomyelitis (EAE). The approach is to develop radioimmunoassays (RIAs) for various defined determinants of MBP that involve 125I-labelled small peptides of known sequence of MBP and antibodies prepared against the peptides. In this connection a synthetic peptide series will be studied in collboration with Dr. George Hashim, St. Luke's Hospital Center, New York City. The defined RIA systems will also be used to search for specific myelin basic protein serum factors (MBP-SFs) among the heterogeneous assay of MBP-SFs that have already been detected in the circulation of Lewis rats, and to prepare and use monospecific immunoadsorbents to isolate and purify individual MBP-SFs. The focus in particular will be upon those encephalitogenic and nearby regions of the MBP molecule involved in EAE inducing and EAE suppressing activity of different species. This part of the investigation will be carried out in collaboration with Dr. P. Y. Paterson, Northwestern University Schools of Medicine and Dentistry, Chicago.